LG SK3D Service Manual

3-1
Copyright © 2021 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
SECTION 3
ELECTRICAL
CONTENTS
WIRING DIAGRAM ............................................................................................................................................ 3-2
BLOCK DIAGRAMS .......................................................................................................................................... 3-3
1. SYSTEM BLOCK DIAGRAM .................................................................................................................. 3-3
2. POWER BLOCK DIAGRAM ................................................................................................................... 3-4
ONE POINT REPAIR GUIDE ............................................................................................................................ 3-5
1.
NO BOOTING WHEN YOU TURN THE UNIT ON, NO MESSAGE OR “HELLO” ON FRONT PANEL ........ 3-5
2. NO SOUND ............................................................................................................................................. 3-9
3. PROTECTION ERROR ......................................................................................................................... 3-12
ELECTRICAL TROUBLESHOOTING GUIDE ................................................................................................. 3-14
1. ADAPTER POWER CIRCUIT ............................................................................................................... 3-14
2. KEY PART ............................................................................................................................................ 3-23
3. USB FUNCTION ................................................................................................................................... 3-24
4. OPTICAL FUNCTION ........................................................................................................................... 3-25
WAVEFORMS OF MAJOR CHECK POINT .................................................................................................... 3-26
1. CRYSTAL .............................................................................................................................................. 3-26
2. FLASH MEMORY ................................................................................................................................. 3-26
3. TACT KEY ............................................................................................................................................. 3-27
4. USB ....................................................................................................................................................... 3-28
5. REMOTE CONTROL ............................................................................................................................ 3-29
6. OPTICAL ............................................................................................................................................... 3-30
7. FM ......................................................................................................................................................... 3-31
CIRCUIT VOLTAGE CHART ........................................................................................................................... 3-33
PRINTED CIRCUIT BOARD DIAGRAMS ....................................................................................................... 3-35
1. MAIN P. C. BOARD DIAGRAM ............................................................................................................ 3-35
2. KEY P. C. BOARD DIAGRAM .............................................................................................................. 3-37

LG SK3D Specifications

General

Brand	LG
Model	SK3D
Category	Speaker System
Language	English